Fits a number of truck models – Peterbilt 379, Freightliner Classic, and Kenworth W900, among others. About 1-1/8″ diameter by 9/16″ tall. Fastens with set screw. Use one of our glossy stickers or aluminum plates to customize this simple knob! This knob can be used for the wiper, washer, fan, dimmer, and panel lights controls. Sold SINGLE.